Grin: [dandelion] specify node address for dandelion stem phase

[antiochp]

Right now its really difficult to test/demonstrate the aggregation behavior via Dandelion.
You can send txs from a couple of nodes but the chances of them actually crossing paths during the stem phase is low.

• we only send txs during stem phase to a single outbound node
• we randomly choose that stem node every 10 mins
• we need to wait for a confirmation before sending a subsequent tx (spend all outputs by default)

It would be useful if we could either -

1. configure a single outbound node in grin.toml to always forward stems txs to, or
2. pass an optional (first hop) node address when sending a tx from the grin command line

This would allow us to get a couple of txs into the same node within a short period of time and have them aggregate on their way through the stem phase with reasonably high success rate.

[beaver-tooth]

Hey I am interested in giving this a whack this weekend.

[sesam]

To get warmed up, you could start with adding a command line option and
print it out like "Dandelion stem added: (partially masked IP)" so it will
show in the logs, but not fully give away where the stem is. I.e. logs
should not give away too much details if grin wants to claim the anonymous
niche.
And on Monday there's a dev meeting on gitter chat, please come join there!

[beaver-tooth]

Thanks @sesam , I will go down this route. I will also try to tune in monday!

[beaver-tooth]

Giving this up, swamped with outside work stuff right now.

[svechinsky]

Is this still necessary?
If so I would like to give it a try

[sesam]

yes I think so. There might be other things more urgent though until mainnet. Once you got grin building and synched up, come into the dev chat for a better update.

[ignopeverell]

Fixed by #2263